Communication semiconductor integrated circuit device and a wireless communication system

ABSTRACT

In a communication semiconductor integrated circuit device using offset PLL architectures and including an oscillator circuit and a frequency divider circuit generating an intermediate frequency signal, the oscillator circuit includes an oscillator, a programmable frequency divider which frequency-divides the oscillation signal in accordance with frequency division information, a phase comparator detecting a phase difference between an output signal of the programmable frequency divider and a reference signal, and a frequency control unit for outputting a signal indicative of the phase difference and controlling the oscillation frequency of the oscillator, wherein a frequency division ratio generator circuit generates an integer part I and a fraction part F/G based on band information concerning the use frequency band and mode information along with channel information and for producing the frequency division ratio information to thereby give it to the programmable frequency divider.

INCORPORATION BY REFERENCE

The present application claims priority from U.K. application 0416117.0filed on Jul. 19, 2004, the content of which is hereby incorporated byreference into this application.

BACKGROUND OF THE INVENTION

The present invention relates to techniques for effective use insemiconductor integrated circuit devices having an on-chip voltagecontrolled oscillator (VCO) and a phase-locked loop (PLL) circuit whichincludes the VCO within its loop. More particularly but not exclusively,the invention relates to techniques for effective use in semiconductorintegrated circuit devices for the communication use employing offsetPLL architectures and having a built-in signal transmission VCO forup-converting the frequency of a transmission signal and a built-in PLLcircuit including the VCO within its loop in a wireless communicationsystem such as for example portable or “mobile” telephone, and alsorelates to wireless communication systems.

In wireless communication systems such as mobile or cellular phones,semiconductor integrated circuit devices for the communication use(referred to as high-frequency ICs hereinafter) are used whichsynthesize a local oscillation signal of high frequency to a receivingsignal and/or a sending signal to thereby perform down-conversion andup-conversion, and which perform modulation of the send signal alongwith demodulation of the receive signal. In such high-frequency ICs,there is the so-called offset PLL architecture for applying quadraturemodulation to transmission I, Q signals using a carrier wave ofintermediate frequency, and also for mixing together a feedback signalfrom the output side of a signal transmission VCO and a high-frequencyoscillation signal from RFVCO to thereby effectuate down conversion intoan intermediate frequency signal equivalent to a frequency difference(offset), and thereafter performing phase comparison of this signal witha signal obtained after the above-noted quadrature modulation to therebycontrol the transmission VCO in accordance with a phase difference thusdetected.

SUMMARY OF THE INVENTION

For the high-frequency ICs of such the offset PLL scheme, an IFVCO whichgenerates the intermediate frequency carrier wave is required inaddition to the transmission VCO and the RFVCO. As the VCO requires arelatively large chip occupation area, a high-frequency IC which isdisclosed for example in JP-A-2003-158452 is designed to use anexternally provided VCO. However, the use of such external VCO wouldresult in an increase in number of parts, and makes miniaturization ordownsizing of IC chips difficult. In view of this, it has been proposedto design the VCO in an on-chip fashion. Unfortunately, letting all ofthe above-noted three VCOs be integrated together on the same chipresults in an increase in chip size, which leads to an increase in chipcost. Additionally, one of those inventions as to the offset PLLscheme-based high-frequency IC is disclosed for example inJP-A-2004-112749.

In order to lessen the chip size of the high-frequency IC with built-inVCOs, the inventors of the present invention herein have studied andconsidered about an approach to reducing the number of VCOs bycommonization of RFVCO and IFVCO-more specifically, deleting IFVCO byfrequency division of an oscillation signal of RFVCO to generate a localsignal of intermediate frequency. As a result, it is possible to set upan appropriate frequency division ratio by a relatively simple logiccircuit if a programmable frequency divider (counter) within the PLLloop including VCO is the one that sets a frequency division ratio of aninteger; however, in the case of setup of such frequency division ratioof the integer, it is possible to switch the oscillation frequency onlyat a frequency interval which is the same as the frequency of areference signal. On the other hand, in the case of commonization ofRFVCO and IFVCO, more precise or “finer” change of the oscillationfrequency becomes necessary. Thus it has been found that it must operatethe programmable frequency divider at a frequency division ratioincluding a decimal number.

Unfortunately, when an attempt is made to build in the high-frequency ICa logic circuit for setting up the frequency division ratio includingthe decimal, the logic circuit becomes larger in scale, and it becomesdifficult to reduce the chip size. Additionally, although there isconsidered another scheme for providing a memory within thehigh-frequency IC to pre-store in this memory all possible frequencydivision ratios corresponding to use frequencies, the significance innumber of the frequency division ratios requires the memory to increasein storage capacity, which leads to an increase in chip size. Inaddition, there may also be considered a method for giving the frequencydivision ratios including decimal numbers from outside of the chip (baseband circuit). However, this approach is faced with a problem whichfollows: an external device such as the baseband circuit fordetermination of the transmission frequency increases in functionsrequired, resulting in a remarkable increase in workload of designerswho attempt to develop and establish a communications system usinghigh-frequency ICs.

It is therefore an object of the present invention to reduce the chipsize of a communication semiconductor integrated circuit device(high-frequency IC) which frequency-divides an oscillation signal ofreference oscillation circuitry RFVCO used for frequency conversion tothereby generate an intermediate frequency carrier wave (local signal),modulates sending I, Q signals by the intermediate frequency carrier,and performs upward conversion into a desired send frequency at atrasmission VCO, and then performs transmission thereof.

Another object of this invention is to lessen the workload of systemdesigners who are responsible for designing a system which uses thecommunication semiconductor integrated circuit device (high-frequencyIC) which frequency-divides an oscillation signal of referenceoscillation circuitry RFVCO used for frequency conversion to therebygenerate an intermediate frequency carrier wave (local signal),modulates the sending I, Q signals by the intermediate frequencycarrier, and performs up conversion to a desired transmission frequencyat a transmission VCO, and then performs transmission thereof.

Still another object of the invention is to simplify logic circuitry forsetup of the frequency division ratio containing a decimal with respectto a programmable frequency divider within a PLL loop including RFVCO tothereby reduce the chip size, in the communication semiconductorintegrated circuit device (high-frequency IC) which does not have IFVCOand which frequency-divides an oscillation signal of RFVCO used forfrequency conversion to thereby generate an intermediate frequencycarrier wave (local signal), modulates sending I, Q signals by theintermediate frequency carrier, and performs up conversion to a desiredtransmission frequency at a transmission VCO, and then performstransmission thereof.

A further object of the invention is to reduce the functions requiredfor external circuitry, that is, a control circuit which determines thetransmission frequency, to thereby lighten the workload of systemdesigners, in the communication-use semiconductor integrated circuitdevice (high-frequency IC) which does not have IFVCO and whichfrequency-divides an oscillation signal of RFVCO used for frequencyconversion to thereby generate an intermediate frequency carrier wave,modulates sending I, Q signals by the intermediate frequency carrier,and performs up conversion to a desired transmission frequency at atransmission VCO, and then performs transmission thereof.

These and other objects and new features of the invention will beapparent from the following more particular description of preferredembodiments of the invention, as illustrated in the accompanyingdrawings.

A brief explanation of summary of some representative ones of theinventive concepts as disclosed herein is as follows.

In a semiconductor integrated circuit device (high-frequency IC) for thecommunication use which employs the offset scheme and which comprises anoscillation circuit for generating an oscillation signal with afrequency pursuant to an externally set value, and a frequency divisioncircuit for frequency division of the oscillation signal as generated bythe oscillation circuit to thereby generate a signal of intermediatefrequency, the oscillation circuit is arranged to include an oscillator(RFVCO), a programmable frequency divider (counter) capable offrequency-dividing an oscillation signal of the oscillator in accordancewith a frequency division ratio supplied thereto, a phase comparator fordetection of a phase difference between an output signal of theprogrammable frequency divider and a reference signal, and a frequencycontrol means for outputting a voltage or a current pursuant to thephase difference detected by the phase comparator and for controllingthe oscillation frequency of the oscillator. There is also provided afrequency division ratio generation circuit for generating an integerpart I and a fraction part F/G based on band information concerning anexternally supplied use frequency band and mode information indicativeof whether signal transmission or reception and also channel informationas to a setup frequency and for generating a frequency division ratiobased on the integer part I and fraction part F/G to thereby give theratio to the programmable frequency divider. More desirably, thefrequency division ratio to be given to the programmable frequencydivider is generated while also referring to the setup information as tothe frequency division ratio of the above-noted frequency dividercircuit.

According to the invention stated above, it is no longer necessary tolet the IFVCO be built in the chip since it generates the intermediatefrequency carrier wave through frequency division of the oscillationsignal of RFVCO. Thus it is possible to reduce the chip size. Inaddition, as it is possible to automatically generate the frequencydivision ratio of programmable frequency divider inside of thesemiconductor chip and then give it to the programmable frequencydivider, it is possible to lessen the information as generated atexternal apparatus such as the base band circuit. Thus it is possible tolighten the workload of users, that is, system designers.

Note here that one desirable arrangement is that the denominator G andnumerator F of the fraction part F/G are arranged to be generated basedon any integer as selected from a combination or combinations of aplurality of integers which are prepared in advance in a waycorresponding to the band information and the frequency division ratiosetup information of the frequency divider circuit. With such anarrangement, it is possible to lessen the scale of the frequencydivision ratio generation circuit for generation of the frequencydivision ratio of the programmable frequency divider including a decimalsuch as represented by an integer part I and fraction part F/G. Thismakes it possible to suppress increase in chip size.

Further desirably, there are provided at the input portion of thesigma-delta modulator a register in which decimal data of the numeratorF of the fraction part F/G to be output from the frequency divisionratio generation circuit can be set from the outside and an adder whichadds together the decimal data being set at the register and thenumerator F. Whereby, even where the frequency of a reference signaldeviates due to variation or fluctuation of the power supply voltagebetween signal sending and receiving sessions, it is possible to correctsuch deviation.

A brief explanation of effects and advantages obtainable by therepresentative ones of the inventive concepts as disclosed herein is asfollows.

In accordance with this invention, since the carrier wave ofintermediate frequency is generated by frequency division of theoscillation signal of RFVCO, it is no longer required to let IFVCO bebuilt in the chip while at the same time enabling simplification oflogic circuitry for setup of the frequency division ratio with respectto the programmable frequency divider (counter) within the PLL loopincluding RFVCO. Thus it is possible to realize a communicationsemiconductor integrated circuit device (high-frequency IC) less in chipsize.

It is also possible to achieve a communication semiconductor integratedcircuit device (high-frequency IC) capable of lessening the functionsrequired for external control circuitry, such as the base band IC fordetermination of the transmission frequency, to thereby enablealleviation of the workload of system designers.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing one example of a communicationsemiconductor integrated circuit device (high-frequency IC) ofmulti-band scheme incorporating the principles of this invention alongwith a wireless communication system using the same.

FIG. 2 is a block diagram showing a configuration example of an RF-PLLin the high-frequency IC of the embodiment, in particular, an RFsynthesizer and a frequency division ratio generator circuit.

FIG. 3 is a block diagram showing a configuration example of a frequencydivision ratio calculator unit making up the frequency division ratiogenerator circuit of FIG. 2.

FIG. 4 is a diagram for explanation of the relationship of an input andan output of a decoder operatively associated with a multiplier MLT1making up the frequency division ratio calculator unit of FIG. 3.

FIG. 5 is an explanation diagram showing the relationship of an inputand an output of a decoder associated with a multiplier MLT2 making upthe frequency division ratio calculator unit of FIG. 3.

FIG. 6 is a block diagram showing an exemplary configuration of asigma-delta modulator making up the frequency division ratio generatorcircuit of FIG. 2.

FIG. 7 is a timing chart showing operation timings of the sigma-deltamodulator of FIG. 6.

FIG. 8 is a timing chart showing operation timings of the frequencydivision ratio generator circuit of FIG. 2.

FIG. 9 is a block diagram showing a configuration example of athree-order sigma-delta modulator for use in a second embodiment of thisinvention.

FIG. 10 is a block diagram showing an exemplary configuration of asigma-delta modulator for use in a third embodiment of the invention.

DESCRIPTION OF THE INVENTION

An explanation will next be given of embodiments of the presentinvention with reference to the accompanying drawings below.

FIG. 1 shows a semiconductor integrated circuit device (high-frequencyIC) for the communication use employing multi-band schemes incorporatingthe principles of this invention along with one example of a wirelesscommunication system using the same.

As shown in FIG. 1, the system is configured from several componentsincluding, but not limited to, an antenna 100 for transmission andreception of signal waves, a switch 110 used for signaltransmit-and-receive changeover, high-frequency filters 120 a to 120 deach including a SAW filter for removing unnecessary waves from areceived signal or the like, a high-frequency power amplifier circuit(power module) 130 for amplification of a sending signal, ahigh-frequency IC 200 which demodulates a received signal and modulatesthe send signal, and a base band circuit 300 which performs basebandprocessing tasks, such as conversion of an audio signal to be sentand/or a data signal into an “I” signal with the same phase component asa fundamental wave and a “Q” signal with an orthogonal componentrelative to the fundamental wave and conversion of the received I and Qsignals thus demodulated into an audio signal or data signal, and whichsends forth a signal for control of the high-frequency IC 200.

Each of the high-frequency IC 200 and the baseband circuit 300 isarranged as a semiconductor integrated circuit on a separate andindividual semiconductor chip. Although not specifically limited, thesystem of the illustrative embodiment is such that the high-frequency IC200 and high-frequency power amplifier circuit 130 are designed tooperate by a power supply voltage Vreg to be supplied from the samevoltage regulator.

Further, although not specifically limited, the high-frequency IC 200 ofthis embodiment is arranged to enable modulation and demodulation ofsignals having four different frequency bands by means of GSM850 andthree communication schemes of GSM900, DCS1800 and PCS1900. In addition,in accordance with this arrangement, the high-frequency filters arearranged so that there are provided a filter 120 a for permittingpass-through of a received signal having the frequency band of PCS1900,a filter 120 b for permitting passage of a receive signal with thefrequency band of DCS1800, and filters 120 c, 120 d for permittingpassage of receive signals in the frequency band of GSM system.

The high-frequency IC 200 of this embodiment is generally constitutedfrom a signal receiver circuit RXC, a signal transmitter circuit TXC,and a control circuit CTC which is made up of circuits in common totransmit-and-receive systems, such as other control circuits, clockgenerator circuitry and the like.

The signal receiver circuit RXC is generally configured from low noiseamplifiers 211 a, 211 b, 211 c, 211 d for amplifying received signals inrespective frequency bands of PCS, DCS and GSM, a frequency-divisionphase shifter circuit 210 which frequency-divides a local oscillationsignal φRF that was generated at a high-frequency oscillation circuit(RFVCO) 262 as will be described later and then generates orthogonalsignals with their phases being offset by 90 degrees to each other,mixers 212 a, 212 b which executes mixing of the orthogonal signals thusgenerated by the frequency-division phase shifter circuit 210 to thereceived signals that are amplified by the low noise amplifiers 211 a,211 b, 211 c, 211 d to thereby perform demodulation and down-conversionoperations, high-gain amplifier units 220A, 220B for amplifying thedemodulated I and Q signals respectively for output to the basebandcircuit 300, and an offset canceler circuit 213 for canceling of aninput DC offset of the amplifiers within the high-gain amplifier unit220A, 220B. The signal receiver circuit RXC of this embodiment employsthe so-called direct conversion scheme for direct down-conversion of areceived signal into a signal in the frequency band of the baseband.

The high-gain amplifier unit 220A is arranged so that a plurality of lowpass filters LPF11, LPF12, LPF13, LPF14 and gain control amplifiersPGA11, PGA12, PGAl3 are alternately connected to have a serialconnection form, with a gain-fixed amplifier AMP1 being connected at thefinal stage, for amplifying the demodulated I signal and then outputtingit to the baseband circuit 300. Similarly the high-gain amplifier unit220B is such that a plurality of low pass filters LPF21, LPF22, LPF23,LPF24 and gain control amps PGA21, PGA22, PGA23 are alternatelyconnected into a series-connection form, with a gain-fixed amplifierAMP2 connected at the final stage, for amplifying the demodulated Qsignal and outputting it to the baseband circuit 300.

The offset canceler circuit 213 is generally made up ofanalog-to-digital conversion (ADC) circuits which are provided in a waycorresponding to respective gain control amplifiers PGA11-PGA23 forconverting into a digital signal an output potential difference of themin the state that input terminals are electrically shorted together,digital-to-analog conversion (DAC) circuits which generate, based onconversion results of these AD converter circuits, input offset voltagesfor letting DC offsets of outputs of corresponding gain controlamplifiers PGA11-23 be set at “0” and then give to a differential input,and a control circuit for controlling these AD converter (ADC) circuitsand DA converter (DAC) circuits and for permitting execution of anoffset canceling operation.

Provided in the controller circuit CTC are a control circuit (controllogic) 260 for control of the entire chip, a reference oscillationcircuit (DCXO) 261 for generating an oscillation signal φref for use asthe reference, a high-frequency oscillation circuit (RFVCO) 262 whichserves as a local oscillator circuit for generating a high-frequencyoscillation signal φRF for the frequency conversion use, an RFsynthesizer 263 which constitutes PLL circuitry together with thehigh-frequency oscillator circuit (RFVCO) 262, a frequency divisionratio generating circuit 264 for generating and giving the frequencydivision ratio of a programmable frequency divider within the RFsynthesizer 263, frequency divider circuits DVD1-DVD2 for frequencydivision of the oscillation signal φRF thus generated by the RFVCO 262,mode changeover switches SW1-SW2 and others.

The switch SW1, SW2 is such that its connection state is changed overbetween a GSM mode which performs signal transmit-and-receive operationsin accordance with the GSM scheme and a DCS/PCS mode which performssignal send-and-receive operations in accordance with either the DCS orPCS scheme, thereby to select the frequency division ratio of a signalbeing transmitted. These switches SW1-SW2 are controlled by a signalfrom the control circuit 260.

There are supplied to the control circuit 260 a clock signal CLK forsynchronization use coming from the baseband circuit 300, a data signalSDATA, and a load enable signal LEN for use as a control signal. Whenthe load enable signal LEN is asserted to an effective level, thecontrol circuit 260 sequentially captures data signals SDATA sent fromthe baseband circuit 300 in synchronization with the clock signal CLKand then generates control signals of chip inside in accordance withcommands contained in the data signals SDATA. The data signals SDATA aresent in a serial fashion, although not specifically limited thereto.

Note here that since the reference oscillation signal φref is requiredto be high in frequency accuracy, an externally provided quartzoscillator is connected to the reference oscillator circuit 261.Typically the reference oscillation signal φref is designed to have aselected frequency of either 26 MHz or 13 MHz. The quartz oscillatorwith such frequency is one of general-purpose electronics components andis readily available in the marketplace. The RF synthesizer 263 is madeup of a frequency divider circuit, phase comparator circuit, chargepump, loop filter and others.

The signal transmitter circuit TXC is generally made up of a frequencydivision circuit 231 which frequency-divides the oscillation signal φRFthat is generated by the RFVCO 262 and generates an oscillation signalφIF of intermediate frequency such as for example 160 MHz, afrequency-division phase-shift circuit 232 which furtherfrequency-divides the signal that was frequency-divided by the frequencydivider circuit 231 and generates orthogonal or quadrature signals withtheir phases being shifted by 90 degrees from each other, modulatorcircuits 233 a, 233 b for modulation of the generated quadrature signalsby the I and Q signals to be supplied from the baseband circuit 300, anadder 234 for synthesizing the signals thus modulated, a signaltransmission oscillator circuit (TXVCO) 234 for generating atransmission signal φTX having a predetermined frequency, an offsetmixer 235 for mixing together a feedback signal that is extracted by acoupler 280 a, 280 b or the like from the send signal φTX as output fromthe transmission oscillator circuit (TXVCO) 234 and a signal φRF′ thatis obtained by frequency division of a high-frequency oscillation signalφRF generated by the high-frequency oscillator circuit (RFVCO) 262 tothereby generate a signal with its frequency equivalent to a differencein frequency between these signals, a phase comparator 236 whichcompares an output of the offset mixer 235 with a signal TXIFsynthesized by the adder 234 to thereby detect a phase difference, aloop filter 237 which generates a voltage pursuant to an output of thephase comparator 236, a frequency divider circuit 238 whichfrequency-divides an output of the transmission oscillator circuit(TXVCO) 234 for creation of a send signal of GSM, and buffer circuits239 a, 239 b for transmission output use.

The transmitter circuit of this embodiment employs the offset PLLarchitecture and operates in such a way as to apply quadraturemodulation to the sending I, Q signals by use of an intermediatefrequency carrier wave and also perform the mixing of a feedback signalfrom the output side of TXVCO 234 and a signal φRF′ that is obtained byfrequency division of the high-frequency oscillation signal φRF of RFVCO262 to thereby execute down-conversion to an intermediate frequencysignal equivalent to a frequency difference (offset) and, thereafter,make phase comparison between this signal and the above-notedquadrature-modulated signal for control of TXVCO 234 in accordance witha phase difference. The phase detector 236, loop filter 237, TXVCO 234and offset mixer 235 constitute a PLL circuit for transmission use(TX-PLL) which performs frequency conversion (up-convert). BFF is abuffer which amplifies the feedback signal extracted by the coupler 280a, 280 b and then supplies it to the mixer 235.

In the multi-band wireless communication system of this embodiment, thecontrol circuit 260 is responsive to a command from the baseband circuit300 as an example for changing, in signal send-and-receive events, thefrequency φRF of an oscillation signal of the high-frequency oscillationcircuit 262 in accordance with an in-use band and channel while at thesame time changing over the above-noted switch SW2 in accordance withwhether GSM mode or DCS/PCS mode, whereby the oscillation signals beingsupplied to the signal receiver circuit RXC and signal transmittercircuit TXC are changed in frequency so that the switching of thesend-and-receive frequency is performed. Furthermore, a control signalfor changeover of the switch SW1, SW2 in response to the signalsend-and-receive frequency band is supplied from the control circuit 260to SW1, SW2. Additionally in this embodiment, the control signal fromcontrol circuit 260 is also used for setup of the frequency divisionratio NIF of frequency divider circuit 231.

The oscillation frequency of RFVCO 262 is set at different values in asignal receiving mode and a sending mode. In the send mode, theoscillation frequency fRF of RFVCO 262 is set, for example, at 3616 to3716 MHz in the case of GSM850, at 3840 to 3980 MHz in the case ofGSM900, and at 3610 to 3730 MHz in the case of DCS, and further at 3860to 3980 MHz in the case of PCS. This is frequency-divided to ¼ at thefrequency divider DVD1, DVD2 in the case of GSM or is frequency-dividedto ½ in the cases of DCS and PCS, and then supplied as φRF′ to theoffset mixer 235 via the switch SW1, SW2.

At the offset mixer 235, a difference signal that is equivalent to adifference in frequency between this φRF′ and the send-use oscillationsignal φTX (i.e., fRF′-fTX) is output and then supplied to the phasecomparator 236. The transmission PLL (TX-PLL) operates in such a waythat the frequency of this difference signal becomes identical to thefrequency of modulation signal TXIF. In other words, TXVCO 234 iscontrolled to oscillate at a frequency corresponding to the differencebetween the frequency (fRF/4 or fRF/2) of oscillation signal φRF′ fromRFVCO 262 and the frequency (fTX) of modulation signal TXIF.

In the receive mode, the oscillation frequency fRF of RFVCO 262 is set,for example, at 3476 to 3576 MHz in the case of GSM850, at 3700 to 3840MHz in the case of GSM900, and at 3610 to 3730 MHz in the case of DCS,and further at 3860 to 3980 MHz in the case of PCS. In the case of GSM,this is frequency-divided to ½ by frequency divider DVD1; alternativelyin the cases of DCS and PCS, it is supplied without frequency divisionto the frequency-division phase shifter circuit 210 whereby frequencydivision and phase shift are done to generate a quadrature signal(s) forsupplement to the mixer 212 a, 212 b.

The RFVCO 262 is made up of an LC resonance type oscillator circuit andothers and is arranged so that a parallel combination of a plurality ofcapacitive elements making up an LC resonator circuit are providedthrough respective switch elements. Such switch elements are caused toselectively turn on in response to a band changeover signal, therebychanging the value of a capacitive element to be connected, that is, thecapacitance value of LC resonator circuit for enabling changeover of theoscillation frequency in a step-like manner. In addition, the RFVCO 262is such that the capacitance value of a variable capacitive element ischanged by a control voltage from the loop filter within RF synthesizer263, permitting the oscillation frequency to change continuously.

In FIG. 2, there is shown one embodiment of the RF-PLL circuit includingthe above-noted RF synthesizer 263 and RFVCO 262.

The PLL circuit of this embodiment comprises a programmable frequencydivider circuit 631 which frequency-divides the oscillation signal φRFof RFVCO 262, a phase comparator circuit 632 for detection of a phasedifference between the reference oscillation signal φref of 26 MHz asgenerated by the reference signal generator circuit (DCXO) 261 and asignal φdiv that is frequency-divided by the programmable frequencydivider circuit 631, a charge pump 633 which determines the use band ofTXVCO 11 in accordance with the phase difference thus detected and whichgenerates and outputs a current Id corresponding to the detected phasedifference, and a loop filter 634 for generating a voltage correspondingto the detected phase difference to be output from the charge pump 633.The PLL circuit is arranged to oscillate at a frequency pursuant to anoscillation control voltage Vt which is smoothened by the loop filter634 and fed back to the RXVCO 262. The programmable frequency dividercircuit 631 is configurable from more than one counter.

Additionally, for setting up the frequency division ratio of theabove-noted programmable frequency divider circuit 631, there isprovided in this embodiment a frequency division ratio generationcircuit (frequency division ratio setup logic) 264 which calculates forsetup the frequency division ratio of programmable frequency dividercircuit 631 from externally supplied channel information CH indicativeof the setup frequency, band information BND indicating whether the useband is GSM850, GSM900, DCS or PCS, mode information T/R indicatingwhether a present mode is the send mode or receive mode, and frequencydivision ratio setting information NIF for setup to the IF frequencydivider 231. The frequency division ratio generator circuit 264 is madeup of a frequency division ratio calculating unit 641, a sigma-deltamodulator 642 with fraction data as its input, and an adder 643. Thechannel information CH is input from the baseband circuit 300 as a valuethat is obtained by dividing either the send frequency or the receivefrequency by 100 kHz.

In this embodiment, the frequency division ratio NIF of IF frequencydivider 231 is set at any one of the values “40”, “44”, “48” and “52”.The reason of this is as follows.

For example, considering a case where the use band is DCS, a presentmode is the transmitting mode, and the transmit frequency is 1713.6 MHz,the case of DCS is such that the transmit frequency band falls within arange of from 1710.2 to 1784.8 MHz whereas the receive frequency rangesfrom 1805.2 to 1879.8 MHz. Additionally, letting the frequency of theoscillation signal φRF of RFVCO 262 be fRF, the frequency of theoscillation signal φTX of send-use VCO 234 be fTX, and the frequency ofthe intermediate frequency signal φIF at the post stage of IF frequencydivider 231 be fIF, the offset PLL is such that fRF′-fTX=fIF; in DCS,fRF′=fRF/2, fRF=fIF×NIF. Due to this, when setting to NIF=44, thefrequency fIF of the intermediate frequency signal φIF at the post of IFfrequency divider 231 is as follows: fIF=2fTX/(NIF-2)=fTX/21=1713.6MHz/21=81.6 MHz. Its 22-time harmonic wave and 23-time harmonic wavebecome 1795.2 MHz and 1876.8 MHz, respectively.

Accordingly in this case, the 22-time harmonic wave causes no problems;however, 1876.8 MHz of 23-time harmonic wave behaves to fall within arange of 1805.2 to 1879.8 MHz of the receive frequency band. Thisresults in the 23-time harmonic wave of the signal φIF passing throughthe mixer 234 and transmitting VCO 234 and then appearing at the outputas a spurious wave. This causes the amount of signal leakage to thereceive frequency to become greater, which leads to the risk that thereceive band noises no longer satisfy the specifications required. Then,setting the frequency division ratio NIF at “40” results in 20-time and21-time harmonic waves becoming problematic matter: these become 1803.8MHz and 1894.0 MHz, respectively. Consequently in this case, the receivefrequency band is out of the range of 1805.2 to 1879.8 MHz so that theproblem of signal leakage to the receive frequency band is avoided.

The same goes with the case where the send frequency is set at otherfrequencies. By shifting the frequency division ratio NIF of the IFfrequency divider 231, it is possible to avoid the leakage of a signalinto the receive frequency band of harmonic wave components of theintermediate frequency signal φIF. This will be referred to hereinafteras the side step of local frequency in the specification. The inventorsof the invention as disclosed and claimed herein have found that it ispossible, by setting the frequency division ratio NIF of IF frequencydivider 231 at a value of “40”, “44”, “48” or “52”, to force thefrequency of harmonic wave of intermediate frequency signal φIF to goout of the receive frequency band even where any frequency is set as thesend frequency. Based on this discovery, the frequency division ratioNIF is set at a specific value selected from the group consisting of“40”, “44”, “48” and “52′”.

Determination of which frequency division ratio is set up from thecombination of the plurality of frequency division ratio NIF values“40”, “44”, “48” and “52” is to be done based on a command coming fromthe baseband circuit 300 side. Thus it is desirable that at the time ofselection of a certain send frequency, high-frequency IC manufacturersor makers prepare in advance a frequency plan indicating which frequencydivision ratio is good for setup and provide such frequency plan tousers, i.e., system designers.

According to this scheme, it becomes possible, by notifying users of theprepared frequency plan which enables the optimum side step, to achievea system that is less in signal leakage to the receive frequency band,which is faced with the risk of significant variability incharacteristics depending on IC layouts.

An explanation will next be given of a method of setting the frequencydivision ratio N to the programmable frequency divider 631 in thehigh-frequency IC of the embodiment stated above.

The relationship of the oscillation frequency fRF of RFVCO 262 versusthe frequency fRX of a received signal in the receiver circuitry of thehigh-frequency IC of this embodiment may be given by the followingequation, by means of the presence of the frequency divider circuit DVD1and switch SW1 and also frequency-division phase shifter circuit 210.

In the case ofGSM850, GSM900: fRF=4·fRX  (1)

In the case ofDCS1800, PCS1900: fRF=2·fRX  (2)

On the other hand, since the transmitter circuitry is of the offset PLLscheme, the relationship of the oscillation frequency fRF of RFVCO 262and the frequency fTX of a send signal may be represented by thefollowing equation, while using the frequency division ratio NIF of theIF-use frequency divider 231 which frequency-divides the oscillationsignal φRF of RFVCO 262 and generates the intermediate frequency signalφIF used for quadrature modulation.

In the case of GSM850, GSM900: from

-   -   fRF/4-fTX=fRF/NIF,        fRF=(¼−1/NIF)⁻¹ ·fTX  (3)

In the case of DCS1800, PCS1900: from

-   -   fRF/2-fTX=fRF/NIF,        fRF=(½−1/NIF)⁻¹ ·fTX  (4)

In addition, the channel information CH is given by the form whichfollows.

In the case of GSM850, GSM900:CH=fRX/100 kHz  (5-1)CH=fTX/100 kHz  (5-2)

In the case of DCS1800, PCS1900:CH=fRX/200 kHz, CH=fTX/200 kHz  (6-1)CH=fRX/200 kHz, CH=fTX/200 kHz  (6-2)

Therefore, the following relationships are established. First, from theEquations (1) and (5-1), in the case of the signal receive mode ofGSM850, GSM900,fRF=4·100 kHz·CH=0.4 MHz·CH  (7)

From the Equations (2) and (6-1), in the case of the receive mode ofDCS1800, PCS1900,fRF=2·200 kHz·CH=0.4 MHz·CH  (8)

From Equations (1) and (5-2), in the case of the send mode of GSM850,GSM900,fRF=(¼−1/NIF)⁻¹·100 kHz·CH  (9)

From Equations (2) and (6-2), in the case of the send mode of DCS1800,PCS1900,fRF=(½−1/NIF)⁻¹·200 kHz·CH  (10)

Here, letting the oscillation signal φref of the reference signalgenerator circuit (DCXO) 261 be set at 26 MHz, the frequency divisionratio N of programmable frequency divider 631 may be given by thefollowing equation.

In the case of the receive mode of GSM850, GSM900:N=fRF/26=(0.4/26)·CH=CH/65  (11)

In the case of the receive mode of DCS1800, PCS1900:N=fRF/26=(0.4/26)·CH=CH/65  (12)

In the case of the send mode of GSM850, GSM900:N=(¼−1/NIF)⁻¹ ·CH/65  (13)

In the case of the send mode of DCS1800, PCS1900:N=(½−1/NIF)⁻¹ ·CH/65  (14)

As apparent from Equations (11) and (12), it can be seen that thedenominator of the frequency division ratio N of programmable frequencydivider 631 in the receive mode is representable by “65”. Additionallyin Equations (13)-(14), the frequency division ratio NIF of IF-usefrequency divider 231 is such that one is selected by the side step fromthe combination of values “40”, “44”, “48” and “52” as has beendescribed previously. Thus it is understandable from Equation (13) thatthe denominator of the frequency division ratio N of programmablefrequency divider 631 at the time of the send mode of GSM850, GSM900 isrepresentable by “585”, 1165011, “715” or “780”. It is understandablefrom Equation (14) that the denominator of the frequency division ratioN of programmable frequency divider 631 at the time of the send mode ofDCS1800, PCS1900 may be given as “1235”, “1365”, “1495” or “1625”.

In view of the foregoing, in order to realize by a single circuit thecombination of denominator values of the programmable frequency divider631 in all possible send and receive events, the least common multipleof 65, 585, 650, . . . , 1625 is set as the denominator. However, thisresults in a significant increase in size of logic circuitry. To avoidthis, in this embodiment, an increase in circuit area is suppressed byusing several techniques which follow.

(1) The denominator is determined from the band information and thefrequency division ratio NIF of the IF frequency divider 231 on acase-by-case basis—say, in a “case-dependent” way.

(2) For the purpose of algorithm commonization, the order of thedenominator is consolidated to range from approximately 1200 to 1700while taking account of the range of 1235 to 1755 at the time of thesend mode of DCS1800, PCS1900.

(3) Any possible errors of the frequency division ratio occurring due tothe alignment of the order of the denominator in the above-noted way isadjustable by adequately modifying the numerator.

FIG. 3 shows an exemplary configuration of the frequency division ratiocalculation unit 641. The frequency division ratio calculator unit 641is generally configured from a multiplier MLT1 which obtains a valuewith X multiplied to the channel information CH, a multiplier MLT2 whichmultiplies a specified constant (65 times) to a value determined fromthe band information BND and frequency division ratio information NIF, adividing circuit DIV1 which reduces an output of the multiplier MLT1 to½ and then outputs its integer part, an adder ADD1 which adds togetheran output of multiplier MLT1 and the integer part as output from thedividing circuit DIV1, a dividing circuit DIV2 which divides an outputof adder ADD1 by an output of multiplier MLT2 and outputs a “quotient”and “remainder,” and a subtracter ASC1 which subtracts an output ofdividing circuit DIV1 from the “remainder” being output from thedividing circuit DIV2. The value of the “quotient” as output from thedividing circuit DIV2 is supplied as integer part data I to theprogrammable frequency divider 631, the value being output from thesubtracter ASC1 is supplied thereto as numerator data F, and the outputof multiplier MLT2 is supplied thereto as denominator data G,respectively. In this specification, “F/G” consisting of the numeratordata F and denominator data G will be called the fraction part data.

Decoders DEC1, DEC2 are provided in the multiplier MLT1 and multiplierMLT2, respectively. The decoder DEC1 decodes the information T/Rindicating whether a present session is signal transmission or receptionand the band information BND and also the frequency division ratioinformation NIF to thereby output the value X for multiplication to theinput channel information CH at the multiplier MLT1. The decoder DEC2decodes the band information BND and frequency division ratioinformation NIF and outputs the value Y for constant-time (65 times)multiplication at the multiplier MLT2. See FIG. 4, which shows therelationship of an input versus an output of the decoder DEC1. FIG. 5shows an input-to-output relationship of the decoder DEC2.

It is apparent from viewing FIGS. 4 and 5 that in case a present mode isthe send mode of GSM with the frequency division ratio NIF being set at“44” by way of example, the X value of the multiplier MLT1 is “22”whereas Y of multiplier MLT2 is “20”. Whereby, in the case of thechannel information CH being set at “8274” (the send frequency is at827.4 MHz), the multiplier MLT1's output CH×22 measures “182028” whilethe denominator data G which is the output of multiplier MLT2 becomes“1300” so that the output of dividing circuit DIV1 is “650”, the outputof adder ADD1 is “182678,” the integer part data I being output from thedividing circuit DIV2 is “140”, and the numerator data F as output fromthe subtracter ASC1 becomes “28”.

Note here that the adder ADD1 and subtracter ASC1 are provided toperform the offset processing, not for letting the fraction part datafall within the range of 0 to 1299 but for letting it range from −650 to+649. The reason of this is as follows: letting the resultant averagevalue be in close proximity to ±0 rather than 650 makes it possible tolessen DC components.

Next, an explanation will be given of a more detailed configuration ofthe sigma-delta modulator 642 in the frequency division ratio generatorcircuit 264 of the embodiment stated supra along with a method forgenerating the frequency division ratio N.

As shown in FIG. 6, the sigma-delta modulator 642 of this embodiment ismade up of an adder ADD2 which adds input numerator data F and feedbackdata together, a 1-bit quantizer QTG1 for quantization of an additionresult, an arithmetic computing unit ALU1 for increasing an output ofthe quantizer QTG1 by factor of a constant number (constant-numbermultiplication), a subtracter ASC2 which obtains a difference between anoutput of the arithmetic unit ALU1 and an output of the adder ADD2, anda delay unit DLY1 which delays the resultant difference for feedback tothe adder ADD2. The sigma-delta modulator operates in synchronizationwith the reference clock signal φref to convert the input numerator datainto data in the time axis direction and then output the data.

The quantizer QTG1 and arithmetic unit ALUL are supplied withdenominator data G from the frequency division ratio calculator unit641. The quantizer QTG1 outputs “+1” when the input is greater than thedenominator data G, outputs “0” when the input falls within a range of 0to G, and outputs “−1” when the input is less than 0. On the other hand,the arithmetic unit ALU1 is such that its gain (multiple number) is setat the same value as the denominator data G as given by the frequencydivision ratio calculator unit 641. This unit increases the input by afactor of G and then outputs it. Although the arithmetic unit ALU1 maybe a multiplier, it is also possible to configure it by a register forsetup of G and a selector or the like which is responsive to an inputfor selecting for output an appropriate one of a present value of theregister or its sign-inverted value or “0”.

Here, an operation of the sigma-delta modulator 642 in case thenumerator data F as input from the frequency division ratio calculatorunit 641 is “28” and the denominator data G is “1300” will be explainedwith reference to FIG. 7.

When the numerator data F is “28,” the output of adder ADD2 increases ina stair step-like pattern with every increment of “28” on a per-clockbasis as shown in (b) of FIG. 7. As the quantizer QTG1 outputs “+1” whenthe input is greater than the denominator data G, it outputs “+1” whenthe output of adder ADD2 goes beyond G (=1300). More specifically, itoutputs “+1” per group of 1300/28 (nearly equal to 47) clocks. As aresult, the sigma-delta modulator 642 is expected to output “+1” for 28times with respect to 1300 reference clocks φref.

Thus it can be seen that the sigma-delta modulator 642 of thisembodiment outputs a specific number of “+1”s, which number is equal tothe number of the fraction data F during a time period of the clocknumber of denominator data G. This is obvious by also taking intoconsideration the fact that when dividing the time period G of referenceclocks φref by a value G/F which is obtained by dividing G that is thethreshold value of quantizer QTG1 by a change amount F of the input, theresult is G÷G/F=F.

FIG. 8 shows the relationship of the integral data I and numerator dataF plus denominator data G as output from the frequency division ratiocalculator unit 641 in the frequency division ratio generator circuit264, the fraction part data F/G as output from the sigma-delta modulator642, and the output frequency division ratio N (=I+F/G) of the adder 643which adds together the integral part data I and fraction part data F/Gand outputs resultant frequency division ratio to the programmablefrequency divider 631. As shown in FIG. 8, in the case of I=140, F=28and G=1300, “141” is output to the programmable frequency divider 631for 28 times during generation of 1300 reference clocks φref; for theremaining 1272 times, “140” is output. More specifically, “141” issupplied as the frequency division ratio N from the frequency divisionratio generator circuit 264 to programmable frequency divider 631 onlyat 28 time points during generation of 1300 reference clocks φref; forthe remaining 1272 times within the 1300 times, “140” is alternativelysupplied as the frequency division ratio N from the frequency divisionratio generator circuit 264 to programmable frequency divider 631. Inaccordance with this frequency division ratio N thus supplied, theprogrammable frequency divider circuit 631 frequency-divides theoscillation signal φRF to thereby form a signal φdiv. It can beconsidered that the signal φdiv thus formed thereby is substantially thesame as a signal which is formed by the programmable frequency dividercircuit 631 through frequency division of the oscillation signal φRF bya frequency division ratio (140+28/1300) of less than the decimal point,when looking at a given time period.

Incidentally, in the one-order or first-degree sigma-delta modulator ofthe embodiment of FIG. 6, there exits in the modulated frequencydivision ratio a periodical repetition or iteration that is, a fixedpattern of prespecified frequency such as in the manner that “141” isregularly output for 28 times with respect to 1300 times, by way ofexample. Although this periodical fixed pattern is at relatively lowfrequency, this is not desirable because it appears as a spuriouscomponent in the output of the RF-PLL which includes the programmablefrequency divider 231.

Consequentially, in order to enable execution of noise shaping byremoval of such periodic fixed pattern being included in thisfirst-order sigma-delta modulator, it has been found that it isdesirable to make use of a higher order of sigma-delta modulator as willbe described below. Note here that a third-order or “cubic” sigma-deltamodulator is used in view of the fact that the use of an extra-highorder of modulator as the high-order sigma-delta modulator would resultin a decrease in the noise shaping effect and also in an excessiveincrease in circuit scale.

FIG. 9 shows an exemplary configuration of a third-order sigma-deltamodulator for use in a second embodiment of the invention.

The sigma-delta modulator of this embodiment comprises three sets ofcircuit modules each equivalent in configuration to an ensemble ofcomponents making up the first-order sigma-delta modulator of FIG. 1namely, the adder ADD2, 1-bit quantizer QTG1, arithmetic unit ALU1,subtracter ASC2 and delay unit DLY1, and is arranged in a way whichfollows: an output of the delay DLY1 at the first stage is input, inplace of F, to a second stage of adder ADD22; an output of thesecond-stage delay DLY2 is input in place of F to a third stage of adderADD23; a value obtained by differentiation of an output of a third stageof 1-bit quantizer QTG3 by a differentiator DFR1 and an output of asecond stage of 1-bit quantizer QTG2 are added together by an adderADD3; and, a value obtained by differentiation of such addition value ata differentiator DFR2 and an output of the first-stage 1-bit quantizerQTG1 are added together by an adder ADD4 and then output. Additionally,delay devices DLY4 and DLY5 are provided for equalization of delayamounts at the first, second and third stages.

Using the third-order sigma-delta modulator makes invisible the fixedpattern of low frequency components as contained in the fraction partdata F/G, thereby permitting output of the one with diffusion towardhigher frequencies. More practically, consider the case of I=140, F=28and G=1300 for example. In this case, “141” is output to theprogrammable frequency divider circuit 631 for 28 times duringgeneration of 1300 reference clocks φref; in addition thereto, “142” and“143” or the like are output along the way of them while at the sametime allowing “138” to be output for the same number of times as theappearance times of “142” in such a way as to cancel out them and alsoletting “137” be output for the same number of times as the appearancetimes of “143.” In short, an averaged result becomes identical to outputof “141” for 28 times.

Whereby, in the case of using the third-order sigma-delta modulatoralso, the frequency division ratio N which is the same as that in thecase of using the first-order sigma-delta modulator is given to theprogrammable frequency divider circuit 631 to thereby reduce occurrenceof spurious ones which “ride” from the output of sigma-delta modulatoronto the output of RF-PLL, resulting in the intended noise-shapingeffect being obtained. It should be noted that the operation ofoutputting “142” and “143” and also “138” and “137” for canceling outthem may be replaced with an operation of outputting “141” for more thanN (N>29) times during generation of 1300 reference clocks φref whileoutputting “139” for (N-28) times on the average, letting “141” beoutput only for 28 times during generation of 1300 reference clocksφref.

An explanation will next be given of a third embodiment of the inventionwith reference to FIG. 10. This embodiment is the one that enablesadjustment of the oscillation frequency of RF-PLL by adding a registerREG0 and an adder ADD0 to the front or “pre” stage of the sigma-deltamodulator 642 of the embodiment of FIG. 6. To be more precise, this isthe one that makes the decimal part data of the frequency division ratioexpandable toward the decimal direction by enabling setup of the data Dof decimal part at the register REG0 and also by causing the adder ADD0to add together the numerator data F and decimal data D for supplementto the adder ADD2. With such an arrangement, in cases where “28” is setup as the numerator data F and “0.025” is set as the decimal data D forexample, the sigma-delta modulator 642 operates to output “+1” for 28025times with respect to 1300000 times, whereby it becomes possible toachieve precise adjustment (fine tuning) of the oscillation frequency ofRF-PLL.

Currently available mobile telephone are faced with the phenomenon thatthe power supply voltage decreases at the time of transmission that usesa power amplifier with large power consumption when compared to theevent of signal reception that uses no power amplifiers. This phenomenonis occurrable obviously in the case of using a battery voltage as thepower supply voltage and also in the case of using a DC-DC convertedvoltage. Due to this, the power supply voltage differs in potentialbetween signal send and receive events, resulting in occurrence oflittle deviation in frequency of the reference oscillator circuit (VCXO)261 which generates the reference oscillation signal φref. Nevertheless,by applying this embodiment and setting the decimal data D at theregister REG0, it becomes possible to avoid such frequency deviation.

It is noted that the decimal data D to be set in the register REG0 maybe arranged to determine by pre-measurement of the oscillation frequencyof the reference oscillator circuit at the time of letting the powersupply voltage vary in potential, and be strored in a rewritablenonvolatile memory such as an EPROM or flash memory or else within thebaseband circuit 300, send the decimal data D also when giving the bandinformation BND and the frequency division ratio information NIF fromthe baseband circuit 300 to high-frequency IC 200, and then set it inthe register REG0. Another arrangement is that a multiplier is providedin place of the adder ADD0 while setting in the register REG0 a valuesuch as for example 1.001 to thereby let the decimal data F become avalue which includes a portion of less than the decimal point.

Although the present invention made by the inventors is explained basedon some embodiments thereof, the invention should not be limitedthereto. For example, in the embodiments stated supra, the one wasexplained which provides within the high-frequency IC the decoder DEC1,DEC2 for generating a certain value to be multiplied to an input at themultiplier MLT1, MLT2 being provided in the frequency division ratiogenerator circuit; however, it may alternatively be arranged to give avalue (see FIG. 4 and FIG. 5) equivalent to the output of decoder fromthe baseband circuit 300 to the high-frequency IC, rather than providingthe decoder DEC1, DEC2.

In addition, although in the above-stated embodiments the frequencydivision ratio NIF of IF-use frequency divider 231 is given from thebaseband circuit 300 external to the chip, if the spurious remedy is nottaken into consideration, then it may be arranged so that theinformation T/R indicating whether the send or receive session and theband information BND plus the channel information CH are used toautomatically determine the frequency division ratio NIF within the chipfor setup in the IF frequency divider 231.

Further note that although in the embodiments stated above are directedto the high-frequency IC with its transmitter circuitry and receivercircuitry formed together on the same semiconductor chip, it is alsopossible to apply to the one that has built-in transmitter circuitry andRF-PLL and is operable to supply an oscillation signal as generated bythe RF-PLL to receiver circuitry that is formed on a separatesemiconductor chip. Additionally, although there was stated previouslythe specific one which is arranged so that the oscillator circuit (VCXO)261 for generation of the signal φref for the reference use is formed onthe same semiconductor chip along with the transmitter circuitry andreceiver circuitry, it may be modified so that the reference signal φrefis given from outside of the chip.

While in the above description the explanation was made while mainlyrelating to certain one which applies this invention made by the presentinventors to frequency divider circuitry making up the RF-PLL inhigh-frequency ICs in the technical field if utilization that becomesthe background of the invention, the invention is not exclusivelylimited thereto, and it is possible to apply the invention to any typesof programmable frequency dividers as designed to perform frequencydivision at frequency division ratios consisting essentially of theso-called the integer part and decimal part. Additionally while in theabove embodiments the explanation is made concerning the case ofapplication to high-frequency ICs for use in wireless communicationssystems such as mobile phones, this invention is not limited thereto andmay also be applicable to high-frequency ICs having PLL circuitry forgenerating a high-frequency signal which is combined together with areceive signal and a send signal for achievement of frequency conversionand modulation/demodulation operations required.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A semiconductor integrated circuit device for communication use, saiddevice comprising: an oscillation circuit for generating an oscillationsignal with a frequency pursuant to an externally set value; a firstfrequency division circuit for frequency division of the oscillationsignal as generated by said oscillation circuit to thereby generate asignal of intermediate frequency; a modulation circuit for modulatingthe signal as frequency-divided by said first frequency divisioncircuit; a first frequency conversion circuit for converting a signalmodulated by said modulation circuit into a transmission signal withhigher frequency; and a second frequency conversion circuit forcombining together a signal taken out of the output side of said firstfrequency conversion circuit and a signal as frequency-divided by asecond frequency division circuit to thereby generate a signal with itsfrequency equivalent to a frequency difference between these signals,said first frequency conversion circuit being arranged to form atransmission signal based on the signal converted by said secondfrequency conversion circuit and the signal modulated by said modulationcircuit, wherein said oscillation circuit includes an oscillator, aprogrammable frequency divider capable of frequency-dividing anoscillation signal of the oscillator in accordance with a frequencydivision ratio supplied thereto, a phase comparator for detection of aphase difference between an output signal of the programmable frequencydivider and a reference signal, and frequency control means foroutputting a voltage or a current pursuant to the phase differencedetected by said phase comparator and for controlling the oscillationfrequency of said oscillator, and said device comprises a frequencydivision ratio generation circuit for generating an integer part I and afraction part F/G based on band information concerning an externallysupplied use frequency band and mode information indicative of whethersignal transmission or reception and channel information as to a setupfrequency, and for generating the frequency division ratio based on saidinteger part I and fraction part F/G.
 2. A communication-usesemiconductor integrated circuit device as recited in claim 1, whereinsaid device further comprises: a third frequency conversion circuit forsynthesizing the oscillation signal generated by said oscillationcircuit or the signal as frequency-divided by said second frequencydivision circuit thereby to convert a received signal into a signallower in frequency.
 3. A communication-use semiconductor integratedcircuit device as recited in claim 1, wherein said frequency divisionratio generation circuit is arranged to generate the frequency divisionratio of said programmable frequency divider based on said bandinformation, said mode information, said channel information, andexternally supplied setup information as to the frequency division ratioof said frequency division circuit.
 4. A communication-use semiconductorintegrated circuit device as recited in claim 3, wherein the denominatorG of said fraction part F/G is arranged to be generated based on anyinteger as selected from a combination of a plurality of integersprepared in advance in a way corresponding to said band information andsaid setup information as to the frequency division ratio.
 5. Acommunication-use semiconductor integrated circuit device as recited inclaim 4, wherein a value for obtaining the numerator F of said fractionpart F/G is arranged to be generated based on any integer as selectedfrom a combination of a plurality of integers prepared in advance in away corresponding to said band information and said mode informationplus said channel information and also based on said setup informationas to the frequency division ratio.
 6. A communication-use semiconductorintegrated circuit device as recited in claim 5, wherein said frequencydivision ratio generation circuit comprises: a frequency division ratiocalculation circuit for outputting as the integer part I a quotientobtained by dividing said value generated based on any integer asselected from the combination of the plurality of integers prepared inadvance in a way corresponding to said band information and said modeinformation plus said channel information and also said setupinformation as to the frequency division ratio by the denominator Ggenerated based on said any integer thus selected while outputting aremainder as the numerator F; and a delta-sigma modulation circuit forusing said denominator G and for performing delta-sigma modulation ofsaid numerator F by using said numerator F to thereby generate thefraction part F/G, wherein the integer part I generated by saidfrequency division ratio calculation circuit and the fraction part F/Ggenerated by said delta-sigma modulation circuit are combined togetherand supplied as a frequency division ratio to said programmablefrequency divider.
 7. A communication-use semiconductor integratedcircuit device as recited in claim 6, wherein said delta-sigmamodulation circuit includes an adder for adding said numerator F for useas input data and feedback data together, a one-bit quantizer forquantization of an addition result, an arithmetic unit for increasing anoutput of the quantizer by a factor of a constant number, a subtracterfor obtaining a difference between an output of the arithmetic unit andan output of the adder, and delay means for delaying the resultantdifference for feedback to said adder.
 8. A communication-usesemiconductor integrated circuit device as recited in claim 7, whereinsaid delta-sigma modulation circuit is a delta-sigma modulation circuitof more than two orders.
 9. A communication-use semiconductor integratedcircuit device as recited in claim 8, wherein the denominator G of saidfraction part F/G is an integral multiple of “65” and is set to fallwithin a range of from 1200 to
 1700. 10. A communication-usesemiconductor integrated circuit device as recited in claim 9, whereinsaid first frequency division circuit is arranged so that the frequencydivision ratio thereof is externally supplied after selection of acertain one from among a plurality of values prepared in advance, saidcertain one being appropriate for preventing harmonic wave components ofthe intermediate frequency signal as frequency-divided by said firstfrequency division circuit from entering a signal reception frequencyband.
 11. A communication-use semiconductor integrated circuit device asrecited in claim 10, wherein a register capable of externally setting avalue which gives decimal number data of the numerator F of saidfraction part F/G to be output from said frequency division ratiogeneration circuit and an arithmetic unit for computing the value beingset in the register and said numerator F are provided in correspondenceto said delta-sigma modulation circuit.
 12. A communication-usesemiconductor integrated circuit device as recited in claim 11, saiddevice further comprising an oscillation circuit for generating saidreference signal.
 13. A wireless communication system comprising: thecommunication-use semiconductor integrated circuit device as claimed inclaim 12; a base band circuit for performing baseband processing oftransmission and reception data; and a high-frequency power amplifierfor power amplification of a transmission signal to be output from saidcommunication-use semiconductor integrated circuit device, wherein saidband information, said mode information, said channel information andthe setup information as to said frequency division ratio are suppliedfrom said base band circuit to said communication-use semiconductorintegrated circuit device.
 14. A wireless communication system asrecited in claim 13, wherein said communication-use semiconductorintegrated circuit device and said high-frequency power amplifier arearranged to operate by a power supply voltage to be supplied from thesame power supply unit.